On a 2000 jetta tdi manual trans. Is it possible to replace the ac clutch without opening the the refrigerant lines?
Is it as easy as loosening the belt.
Using a clutch/pulley puller and replacing i t with a new one?
Do i need to lockdown the compressor from turning? how?
Thanks for any response.
Also where can i source just the AC clutch/pulley/magnet ?

I haven't done it on the jetta yet, but on my Saab it was as easy as putting the car up on jackstands, dropping the compressor down (there is enough hose to allow some working room) and remove the clutch/pulley. The clutch is typically a plate on the very outside of the pulley and may not even require removing the compressor from its mount. It should be very easy to do since its right on the bottom of the car.
Question is, can you get a clutch plate seperately? It may be wise to do the bearing at the same time if you're going to all this trouble. They tend to go bad about the same time and will leave you stranded if it really goes bad.

I looked around and can't see just the clutch for sale anywhere. This is typical though. Most manufacturers don't sell the individual parts, though you could probably find them directly as I did in the case of my saab's compressor bearing which had failed. Naturally, the shops all wanted me to buy a $500 compressor to fix what turned out to be $40 bucks in parts. I was able to find the bearing and clutch from a place called Polar Bear AC supply. Look them up on the web. They sell many of the individual mechanical parts for these compressors, but you will need to know the model of compressor. They don't have a way to cross reference to the type of car usually.

To answer the original question - you do not loose any refrigerant. Remove the belt then remove the center nut. To do this you'll need to hold the end plate still. I was able to grab one of the nubs with pliers (Beetle was a little tight). Once that plate comes off there is a circlip holding the pulley on. Behind that is a circlip holding the coil in place. The owner of the car I was working on bought a whole used compressor just for the clutch and it was relatively cheap.

I did mine on stands from underneath. It's not a bad job at all. I decided to replace the bearings, plate, and clutch magnet all together rather than get a "built in who knows where" aftermarket compressor.

I got the clutch replaced and it worked perfect for several weeks. Now today, it doesn't cool anymore. If you turn the A/C off, it makes a terrible noise.

I got under it and checked it, and the front plate free spins... and the nut and shaft don't spin with the plate. I put a socket on the nut to try to take it off, and I could spin the nut which was turning the compressor shaft. I could turn it with the socket with just using my fingers.